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townaj Member
Joined: 04 Dec 2008 Posts: 326 Location: San Antone, TX
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Posted: Fri Oct 29, 2010 8:04 pm Post subject: New parts and new problems!! |
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| Hey guys I haven't been on in a while but now I'm back! With some shiny new parts and shiny new problems to go with them. Just in case y'all don't remember I have a 383 backed by a nwc t5. I now have a rebuilt 750 double Pumper Holley and a new air gap-type intake. It runs even better now, but I'm having charging issues. My old alternator stopped charging so I replaced it with multiple rebuilt units thinking it went bad after 25 years. Wrong. After going through 2 alternators I figure its something with the car. But I don't know what. All the connections are good and its hooked up right, but it still refuses to charge. Any ideas? I need to get this thing back on the road asap! Thanks guys... |
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Fri Oct 29, 2010 8:37 pm Post subject: |
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Excite wire not switching properly from ignition.
Crap battery.
Sense wire reading to much voltage.
Number one is the most likely culprit. |
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townaj Member
Joined: 04 Dec 2008 Posts: 326 Location: San Antone, TX
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Posted: Fri Oct 29, 2010 9:10 pm Post subject: |
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| Battery is good. Had it tested etc. How would I test for the excite wire and fix it? Would it be at the ignition switch? |
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Fri Oct 29, 2010 9:14 pm Post subject: |
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| Check for 12V at the small tan/white/brown wire (whatever is not the big one) while the ignition switch is on. |
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townaj Member
Joined: 04 Dec 2008 Posts: 326 Location: San Antone, TX
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Posted: Fri Oct 29, 2010 9:35 pm Post subject: |
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| The one that comes through the firewall? Its got hardly anything...so its disconnected from something? |
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Al Hasse Member

Joined: 19 Nov 2005 Posts: 4379 Location: Bremerton, WA
1992 Chevrolet Camaro RS
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Posted: Fri Oct 29, 2010 10:03 pm Post subject: |
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IIRC that should be connected to either a resistor or a light bulb in the dash. That's where it gets the excitation from. _________________ 92 Camaro
89 Camaro
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Sat Oct 30, 2010 7:19 am Post subject: |
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| Al Hasse wrote: | | IIRC that should be connected to either a resistor or a light bulb in the dash. That's where it gets the excitation from. |
Bingo. You can also run a diode in place of the resistor or 'Gen' light; basically you need something to keep the alt from back-feeding the coil.
The problem is that on a lot of these cars the wires going into the smaller plug on the alt get kinked and lose connection. If the alt never excites, it basically thinks the car is off all the time. |
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iansane Member

Joined: 16 Jan 2004 Posts: 5742 Location: Bothell
1991 Pontiac Trans Am
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Posted: Sat Oct 30, 2010 10:00 am Post subject: |
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My excite wire was hooked to the 20a fan fuse. Someone stole that fuse when I was at a bar one night. That took awhile to find.  _________________
| Quote: | | Sometimes I actually think I'm slightly retarded in the mouth. |
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Sat Oct 30, 2010 10:40 am Post subject: |
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If only your car had a roof, to prevent such nonsense.
Actually, I think that was stock from Chebbie. IIRC the fan fuse is actually just a bunch of low-draw crap that gets triggered when the ignition switch is on (the fan relay and alternator excite wire, for instance ) |
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iansane Member

Joined: 16 Jan 2004 Posts: 5742 Location: Bothell
1991 Pontiac Trans Am
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Posted: Sat Oct 30, 2010 10:50 am Post subject: |
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| aaron_sK wrote: | If only your car had a roof, to prevent such nonsense.
Actually, I think that was stock from Chebbie. IIRC the fan fuse is actually just a bunch of low-draw crap that gets triggered when the ignition switch is on (the fan relay and alternator excite wire, for instance ) |
Yeah, it was factory. I was pouring over the wiring diagrams after checking the battery/alt and then realizing I was getting nothing on the excite wire.
Now that's my biggest push at work. Someone says their alt isn't working but tests fine, "Dude, you sure it's getting excited?" And they get all confused.  _________________
| Quote: | | Sometimes I actually think I'm slightly retarded in the mouth. |
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townaj Member
Joined: 04 Dec 2008 Posts: 326 Location: San Antone, TX
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Posted: Sat Oct 30, 2010 10:06 pm Post subject: |
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| Haha well it turns out the excite wire was smashed between the steering column mounting ears and that metal plate it sits against. It was nice and flat when I got it outta there. Fixed the wire and now it charges. At least I got a new alternator lol. Y'all are awesome thanks for the help. I'm almost ready to paint it. Just gotta buy the clear coat. |
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